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How about the 4 stroke dirt bike motors?

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  • steveschollmeier
    I, like many of you am looking for a lightweight 4-stroke to fit into an ultralight. Has anyone looked into the current wave of 4 strokes which are dominating
    Message 1 of 7 , Apr 1 9:36 AM
      I, like many of you am looking for a lightweight 4-stroke to fit into
      an ultralight. Has anyone looked into the current wave of 4 strokes
      which are dominating the professional motocross scene the last several
      years? The popular engine sizes are 250cc and 450cc and they are
      putting out more power than their replacement 125cc & 250cc 2-strokes.
      I have no idea what they weigh but it can't be very much for them to be
      blowing away the 2-strokes. (I've tried to find info as far as hp &
      weight of these engines without much luck. I've heard from dealerships
      a typcial 450cc 4 stroke is around 50hp.)

      Anyone have info about these motors I'd love to hear from them.

      Sincerely,

      Steve Schollmeier
    • rb4no
      I think that the old 2 strokes put out more hp however, the 4 stroke 450´s have much higher torque rating´s which make them very tractable, saying that a 2
      Message 2 of 7 , Apr 3 11:27 AM
        I think that the old 2 strokes put out more hp however, the 4 stroke
        450´s have much higher torque rating´s which make them very tractable,
        saying that a 2 stroke 250 are readily available and max out at aprox
        8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
        13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
        it was going for a bomb, something like $1200 for the engine and it
        still had a few day´s left to go.

        --- In Small4-strokeEngines@yahoogroups.com, "steveschollmeier"
        <caddad1@...> wrote:
        >
        > I, like many of you am looking for a lightweight 4-stroke to fit into
        > an ultralight. Has anyone looked into the current wave of 4 strokes
        > which are dominating the professional motocross scene the last several
        > years? The popular engine sizes are 250cc and 450cc and they are
        > putting out more power than their replacement 125cc & 250cc 2-strokes.
        > I have no idea what they weigh but it can't be very much for them to be
        > blowing away the 2-strokes. (I've tried to find info as far as hp &
        > weight of these engines without much luck. I've heard from dealerships
        > a typcial 450cc 4 stroke is around 50hp.)
        >
        > Anyone have info about these motors I'd love to hear from them.
        >
        > Sincerely,
        >
        > Steve Schollmeier
        >
      • Brad Heiter
        Hi, I ve looked at the Honda CRF450. I think it s possible but the service manual IIRC calls for piston replacment at 10 hours and that s for a motorcycle
        Message 3 of 7 , Apr 3 12:53 PM
          Hi, I've looked at the Honda CRF450. I think it's possible but the service manual IIRC calls for piston replacment at 10 hours and that's for a motorcycle duty cycle not aircraft use. Then the price is rather high, atleast for my budget. My intention was to lower it's peak torque RPM by cam retiming, exhuast tuning and intake tuning but to get the rpm down to were you could use the stock primary gears as the redrive it looks like you'd have about 25 to 30 HP. I'm still looking for other options.
          Brad H
          ----- Original Message -----
          From: rb4no
          To: Small4-strokeEngines@yahoogroups.com
          Sent: Tuesday, April 03, 2007 1:27 PM
          Subject: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?


          I think that the old 2 strokes put out more hp however, the 4 stroke
          450´s have much higher torque rating´s which make them very tractable,
          saying that a 2 stroke 250 are readily available and max out at aprox
          8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
          13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
          it was going for a bomb, something like $1200 for the engine and it
          still had a few day´s left to go.

          --- In Small4-strokeEngines@yahoogroups.com, "steveschollmeier"
          <caddad1@...> wrote:
          >
          > I, like many of you am looking for a lightweight 4-stroke to fit into
          > an ultralight. Has anyone looked into the current wave of 4 strokes
          > which are dominating the professional motocross scene the last several
          > years? The popular engine sizes are 250cc and 450cc and they are
          > putting out more power than their replacement 125cc & 250cc 2-strokes.
          > I have no idea what they weigh but it can't be very much for them to be
          > blowing away the 2-strokes. (I've tried to find info as far as hp &
          > weight of these engines without much luck. I've heard from dealerships
          > a typcial 450cc 4 stroke is around 50hp.)
          >
          > Anyone have info about these motors I'd love to hear from them.
          >
          > Sincerely,
          >
          > Steve Schollmeier
          >





          [Non-text portions of this message have been removed]
        • Noel Loveys
          I think you may have a typo there. Not even formula racers would change their pistons at 10 hr. would they? I could see 1000 hr. Even that would be a short
          Message 4 of 7 , Apr 3 2:53 PM
            I think you may have a typo there. Not even formula racers would change
            their pistons at 10 hr. would they? I could see 1000 hr. Even that would be
            a short life.



            Noel

            -----Original Message-----
            From: Small4-strokeEngines@yahoogroups.com
            [mailto:Small4-strokeEngines@yahoogroups.com] On Behalf Of Brad Heiter
            Sent: Tuesday, April 03, 2007 5:23 PM
            To: Small4-strokeEngines@yahoogroups.com
            Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
            motors?



            Hi, I've looked at the Honda CRF450. I think it's possible but the service
            manual IIRC calls for piston replacment at 10 hours and that's for a
            motorcycle duty cycle not aircraft use. Then the price is rather high,
            atleast for my budget. My intention was to lower it's peak torque RPM by cam
            retiming, exhuast tuning and intake tuning but to get the rpm down to were
            you could use the stock primary gears as the redrive it looks like you'd
            have about 25 to 30 HP. I'm still looking for other options.
            Brad H
            ----- Original Message -----
            From: rb4no
            To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
            s@yahoogroups.com
            Sent: Tuesday, April 03, 2007 1:27 PM
            Subject: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?

            I think that the old 2 strokes put out more hp however, the 4 stroke
            450´s have much higher torque rating´s which make them very tractable,
            saying that a 2 stroke 250 are readily available and max out at aprox
            8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
            13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
            it was going for a bomb, something like $1200 for the engine and it
            still had a few day´s left to go.

            --- In Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
            s@yahoogroups.com, "steveschollmeier"
            <caddad1@...> wrote:
            >
            > I, like many of you am looking for a lightweight 4-stroke to fit into
            > an ultralight. Has anyone looked into the current wave of 4 strokes
            > which are dominating the professional motocross scene the last several
            > years? The popular engine sizes are 250cc and 450cc and they are
            > putting out more power than their replacement 125cc & 250cc 2-strokes.
            > I have no idea what they weigh but it can't be very much for them to be
            > blowing away the 2-strokes. (I've tried to find info as far as hp &
            > weight of these engines without much luck. I've heard from dealerships
            > a typcial 450cc 4 stroke is around 50hp.)
            >
            > Anyone have info about these motors I'd love to hear from them.
            >
            > Sincerely,
            >
            > Steve Schollmeier
            >

            [Non-text portions of this message have been removed]







            [Non-text portions of this message have been removed]
          • Brad Heiter
            Sorry, My memory was wrong. I just checked my 2003 service manual and piston and rings should be changed every 15 hours of use. Thats the same interval as
            Message 5 of 7 , Apr 3 3:33 PM
              Sorry, My memory was wrong. I just checked my 2003 service manual and piston and rings should be changed every 15 hours of use. Thats the same interval as the oil and filter. I bought my 2003 CRF450 new from Canada (exchange rate was good) and it came with a spares kit: 1) airfilter, 1) oil filter, 1) front brake lever, 1) top end gasket kit, 1) piston, 1) set of rings and the manual. I'm sure that schedule is for a Pro but even a Pro can't use 70% power for hours on end. That said, with an enlarged oil capacity they have been run by Pro's in 24 hour competitions and most fairly stock ones finish. The dry engine oil quantity is 0.85 liters and oil and filter change refill quantity is 0.69 liters. The piston is a disc just tall enough to have a place for the two rings with two bosses on the bottom for the piston pin and the "skirt" is not much bigger than the first joint of my thumb. So I'm sure if the RPM's came down and a more standard piston fitted reliablity would go up. But I'd suggest test test test before flying one.
              Cheers,
              Brad
              ----- Original Message -----
              From: Noel Loveys
              To: Small4-strokeEngines@yahoogroups.com
              Sent: Tuesday, April 03, 2007 4:53 PM
              Subject: RE: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?


              I think you may have a typo there. Not even formula racers would change
              their pistons at 10 hr. would they? I could see 1000 hr. Even that would be
              a short life.



              Noel

              -----Original Message-----
              From: Small4-strokeEngines@yahoogroups.com
              [mailto:Small4-strokeEngines@yahoogroups.com] On Behalf Of Brad Heiter
              Sent: Tuesday, April 03, 2007 5:23 PM
              To: Small4-strokeEngines@yahoogroups.com
              Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
              motors?

              Hi, I've looked at the Honda CRF450. I think it's possible but the service
              manual IIRC calls for piston replacment at 10 hours and that's for a
              motorcycle duty cycle not aircraft use. Then the price is rather high,
              atleast for my budget. My intention was to lower it's peak torque RPM by cam
              retiming, exhuast tuning and intake tuning but to get the rpm down to were
              you could use the stock primary gears as the redrive it looks like you'd
              have about 25 to 30 HP. I'm still looking for other options.
              Brad H
              ----- Original Message -----
              From: rb4no
              To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
              s@yahoogroups.com
              Sent: Tuesday, April 03, 2007 1:27 PM
              Subject: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?

              I think that the old 2 strokes put out more hp however, the 4 stroke
              450´s have much higher torque rating´s which make them very tractable,
              saying that a 2 stroke 250 are readily available and max out at aprox
              8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
              13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
              it was going for a bomb, something like $1200 for the engine and it
              still had a few day´s left to go.

              --- In Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
              s@yahoogroups.com, "steveschollmeier"
              <caddad1@...> wrote:
              >
              > I, like many of you am looking for a lightweight 4-stroke to fit into
              > an ultralight. Has anyone looked into the current wave of 4 strokes
              > which are dominating the professional motocross scene the last several
              > years? The popular engine sizes are 250cc and 450cc and they are
              > putting out more power than their replacement 125cc & 250cc 2-strokes.
              > I have no idea what they weigh but it can't be very much for them to be
              > blowing away the 2-strokes. (I've tried to find info as far as hp &
              > weight of these engines without much luck. I've heard from dealerships
              > a typcial 450cc 4 stroke is around 50hp.)
              >
              > Anyone have info about these motors I'd love to hear from them.
              >
              > Sincerely,
              >
              > Steve Schollmeier
              >

              [Non-text portions of this message have been removed]

              [Non-text portions of this message have been removed]





              [Non-text portions of this message have been removed]
            • Noel Loveys
              What is the redline of that engine? it sounds like a 10,000prm+ job. Noel ... From: Small4-strokeEngines@yahoogroups.com
              Message 6 of 7 , Apr 4 4:22 PM
                What is the redline of that engine? it sounds like a 10,000prm+ job.



                Noel

                -----Original Message-----
                From: Small4-strokeEngines@yahoogroups.com
                [mailto:Small4-strokeEngines@yahoogroups.com] On Behalf Of Brad Heiter
                Sent: Tuesday, April 03, 2007 8:04 PM
                To: Small4-strokeEngines@yahoogroups.com
                Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                motors?



                Sorry, My memory was wrong. I just checked my 2003 service manual and piston
                and rings should be changed every 15 hours of use. Thats the same interval
                as the oil and filter. I bought my 2003 CRF450 new from Canada (exchange
                rate was good) and it came with a spares kit: 1) airfilter, 1) oil filter,
                1) front brake lever, 1) top end gasket kit, 1) piston, 1) set of rings and
                the manual. I'm sure that schedule is for a Pro but even a Pro can't use 70%
                power for hours on end. That said, with an enlarged oil capacity they have
                been run by Pro's in 24 hour competitions and most fairly stock ones finish.
                The dry engine oil quantity is 0.85 liters and oil and filter change refill
                quantity is 0.69 liters. The piston is a disc just tall enough to have a
                place for the two rings with two bosses on the bottom for the piston pin and
                the "skirt" is not much bigger than the first joint of my thumb. So I'm sure
                if the RPM's came down and a more standard piston fitted reliablity would go
                up. But I'd suggest test test test before flying one.
                Cheers,
                Brad
                ----- Original Message -----
                From: Noel Loveys
                To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups.com
                Sent: Tuesday, April 03, 2007 4:53 PM
                Subject: RE: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                motors?

                I think you may have a typo there. Not even formula racers would change
                their pistons at 10 hr. would they? I could see 1000 hr. Even that would be
                a short life.

                Noel

                -----Original Message-----
                From: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups.com
                [mailto:Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups.com] On Behalf Of Brad Heiter
                Sent: Tuesday, April 03, 2007 5:23 PM
                To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups.com
                Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                motors?

                Hi, I've looked at the Honda CRF450. I think it's possible but the service
                manual IIRC calls for piston replacment at 10 hours and that's for a
                motorcycle duty cycle not aircraft use. Then the price is rather high,
                atleast for my budget. My intention was to lower it's peak torque RPM by cam
                retiming, exhuast tuning and intake tuning but to get the rpm down to were
                you could use the stock primary gears as the redrive it looks like you'd
                have about 25 to 30 HP. I'm still looking for other options.
                Brad H
                ----- Original Message -----
                From: rb4no
                To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups. <mailto:s%40yahoogroups.com> com
                Sent: Tuesday, April 03, 2007 1:27 PM
                Subject: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?

                I think that the old 2 strokes put out more hp however, the 4 stroke
                450´s have much higher torque rating´s which make them very tractable,
                saying that a 2 stroke 250 are readily available and max out at aprox
                8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
                13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
                it was going for a bomb, something like $1200 for the engine and it
                still had a few day´s left to go.

                --- In Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                s@yahoogroups. <mailto:s%40yahoogroups.com> com, "steveschollmeier"
                <caddad1@...> wrote:
                >
                > I, like many of you am looking for a lightweight 4-stroke to fit into
                > an ultralight. Has anyone looked into the current wave of 4 strokes
                > which are dominating the professional motocross scene the last several
                > years? The popular engine sizes are 250cc and 450cc and they are
                > putting out more power than their replacement 125cc & 250cc 2-strokes.
                > I have no idea what they weigh but it can't be very much for them to be
                > blowing away the 2-strokes. (I've tried to find info as far as hp &
                > weight of these engines without much luck. I've heard from dealerships
                > a typcial 450cc 4 stroke is around 50hp.)
                >
                > Anyone have info about these motors I'd love to hear from them.
                >
                > Sincerely,
                >
                > Steve Schollmeier
                >

                [Non-text portions of this message have been removed]

                [Non-text portions of this message have been removed]

                [Non-text portions of this message have been removed]







                [Non-text portions of this message have been removed]
              • Brad Heiter
                I don t know what redline is but dyno runs I ve seen show it making about 32lbs/ft of torque at 7000 rpm and 45 rear wheel hp at 8000rpm. Brad H ... From: Noel
                Message 7 of 7 , Apr 4 4:33 PM
                  I don't know what redline is but dyno runs I've seen show it making about 32lbs/ft of torque at 7000 rpm and 45 rear wheel hp at 8000rpm.

                  Brad H
                  ----- Original Message -----
                  From: Noel Loveys
                  To: Small4-strokeEngines@yahoogroups.com
                  Sent: Wednesday, April 04, 2007 6:22 PM
                  Subject: RE: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?


                  What is the redline of that engine? it sounds like a 10,000prm+ job.



                  Noel

                  -----Original Message-----
                  From: Small4-strokeEngines@yahoogroups.com
                  [mailto:Small4-strokeEngines@yahoogroups.com] On Behalf Of Brad Heiter
                  Sent: Tuesday, April 03, 2007 8:04 PM
                  To: Small4-strokeEngines@yahoogroups.com
                  Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                  motors?

                  Sorry, My memory was wrong. I just checked my 2003 service manual and piston
                  and rings should be changed every 15 hours of use. Thats the same interval
                  as the oil and filter. I bought my 2003 CRF450 new from Canada (exchange
                  rate was good) and it came with a spares kit: 1) airfilter, 1) oil filter,
                  1) front brake lever, 1) top end gasket kit, 1) piston, 1) set of rings and
                  the manual. I'm sure that schedule is for a Pro but even a Pro can't use 70%
                  power for hours on end. That said, with an enlarged oil capacity they have
                  been run by Pro's in 24 hour competitions and most fairly stock ones finish.
                  The dry engine oil quantity is 0.85 liters and oil and filter change refill
                  quantity is 0.69 liters. The piston is a disc just tall enough to have a
                  place for the two rings with two bosses on the bottom for the piston pin and
                  the "skirt" is not much bigger than the first joint of my thumb. So I'm sure
                  if the RPM's came down and a more standard piston fitted reliablity would go
                  up. But I'd suggest test test test before flying one.
                  Cheers,
                  Brad
                  ----- Original Message -----
                  From: Noel Loveys
                  To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups.com
                  Sent: Tuesday, April 03, 2007 4:53 PM
                  Subject: RE: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                  motors?

                  I think you may have a typo there. Not even formula racers would change
                  their pistons at 10 hr. would they? I could see 1000 hr. Even that would be
                  a short life.

                  Noel

                  -----Original Message-----
                  From: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups.com
                  [mailto:Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups.com] On Behalf Of Brad Heiter
                  Sent: Tuesday, April 03, 2007 5:23 PM
                  To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups.com
                  Subject: Re: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike
                  motors?

                  Hi, I've looked at the Honda CRF450. I think it's possible but the service
                  manual IIRC calls for piston replacment at 10 hours and that's for a
                  motorcycle duty cycle not aircraft use. Then the price is rather high,
                  atleast for my budget. My intention was to lower it's peak torque RPM by cam
                  retiming, exhuast tuning and intake tuning but to get the rpm down to were
                  you could use the stock primary gears as the redrive it looks like you'd
                  have about 25 to 30 HP. I'm still looking for other options.
                  Brad H
                  ----- Original Message -----
                  From: rb4no
                  To: Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups. <mailto:s%40yahoogroups.com> com
                  Sent: Tuesday, April 03, 2007 1:27 PM
                  Subject: [Small4-strokeEngines] Re: How about the 4 stroke dirt bike motors?

                  I think that the old 2 strokes put out more hp however, the 4 stroke
                  450´s have much higher torque rating´s which make them very tractable,
                  saying that a 2 stroke 250 are readily available and max out at aprox
                  8 - 9000 rpm instead of the 4 strokes which max out at somewhere like
                  13-14,000 rpm. I saw a yamaha 250 4 stroke on ebay the other day and
                  it was going for a bomb, something like $1200 for the engine and it
                  still had a few day´s left to go.

                  --- In Small4-strokeEngine <mailto:Small4-strokeEngines%40yahoogroups.com>
                  s@yahoogroups. <mailto:s%40yahoogroups.com> com, "steveschollmeier"
                  <caddad1@...> wrote:
                  >
                  > I, like many of you am looking for a lightweight 4-stroke to fit into
                  > an ultralight. Has anyone looked into the current wave of 4 strokes
                  > which are dominating the professional motocross scene the last several
                  > years? The popular engine sizes are 250cc and 450cc and they are
                  > putting out more power than their replacement 125cc & 250cc 2-strokes.
                  > I have no idea what they weigh but it can't be very much for them to be
                  > blowing away the 2-strokes. (I've tried to find info as far as hp &
                  > weight of these engines without much luck. I've heard from dealerships
                  > a typcial 450cc 4 stroke is around 50hp.)
                  >
                  > Anyone have info about these motors I'd love to hear from them.
                  >
                  > Sincerely,
                  >
                  > Steve Schollmeier
                  >

                  [Non-text portions of this message have been removed]

                  [Non-text portions of this message have been removed]

                  [Non-text portions of this message have been removed]

                  [Non-text portions of this message have been removed]





                  [Non-text portions of this message have been removed]
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